With seasonal affective disorder and winder blues, light lux (the total light energy in the human visible spectrum), is the main component needed to be measured and tracked over time. However, recording the light colour components also has important benefits for analysis. First, it allows improved automatic tagging for light environment types, where the colour temperature and colour tint allow a better characterisation of the kind of light you’re being exposed to (e.g. fluorescent office lighting vs. natural outdoor light, or bright but overcast days vs. clear blue sky days). This extra information can be used to generate high level, dashboard like views of each day, week, month and year – do you know how many hours of direct sunshine you had this week? The second use of colour data is in measuring the amount of the shorter wavelength (blue) light you are exposed to. Studies suggest blue light is more effective at triggering cells in your eye’s retina responsible for maintaining your circadian rhythm – stimulating serotonin production and inhibiting melatonin, keeping you alert and clear during waking hours. Avoiding blue wavelengths for a few hours before you try and sleep allows melatonin levels to naturally rise, helping you have restful, refreshing sleep.